Perhaps if we could retexture barrier blocks with a certain damage value. 0 could be the default (invisible), then each damage value gets its own texture based on the resource pack. (textures/blocks/barriers/barrier1 , barrier2, etc.)

Retexturing a block full black does exactly this, if it's supposed to be on a server or an adventure map. No shading, no slightly lighter parts, pitch black hexagon, rectangle or square, depending the direction.

oooooh that actually sounds quite cool if i decided to do a haunted map i could block off areas with smoke particlesa and then a black barrier wall.... that might add quite a bit of atmosphere in my builds